Method of treating and removing finely divided solid material



LIS." Fulk mw\ Q huist-U |l. o n l|| u. my m m WMM.. Q 3.. L J||l mm J r .\\N m E. www@ 2,. MM @N.. L r MN NbLtNvun. o@ w m w da, a W. M 95. dw2 ou! Z I# d., Ml www pk. n w m NN QN H mw c. M m m www', .4, H m F mm m. mm, Nok touwkk a n Y .mi a, H m A J.. M uw I1 .lexutxllnf Mmwldn m l EN |.\1 r WMM w Patented July ,10, 194s t METIOD F TREATING AND REMOVING FINELY DIVIDED SOLID i John C. Munday, Cranford, N. J., assigner to pment Company,`a cor- Standard Oil Deveio poration of Delaware Application January 4, 1941, Serial No. 373,112

2 Claims. (Cl. 196-52) This invention relates to a process of and apparatus for carrying out catalytic reactions and pertains more particularly .to processes and ap-v paratus wherein the catalyst; in finely-divided form is introduced into a stream of gases to be reacted and' the resulting' mixture passed through a reaction zone.

While the invention in its broader phases has a more general application, it is particularly suitable for the cracking of higher boiling hydrocarbon oils into lower boiling-oils, such as motor fuels, diesel fuels, kerosenes, and the like.

It has heretofore been proposed'to crack petroleum oils by first intermixing finely-divided catalyst with the oil vapors to be cracked and then passing the resulting mixture through a cracking zone maintained at the desired temperature for bringing about the cracking operation. Following the cracking operation, the catalyst is separated from the cracked products and the cracked products fractionated to segregate the motor fuel or other low boiling distillates from the insufliciently cracked higher boiling oil and the gaseous constituents formed during the cracking operation. The catalyst separated-from the cracked products is normally subjected .to a regenerative treatment to remove combustible deposits which accumulate during the cracking operation. Following the regenerative treatment, the catalyst is returned to the cracking zone for further use. Y

When operating according to this general .type of procedure, difficulty has been encountered in introducing the catalyst into the stream of oil Yvapors. This dirllculty is due in a large measinto the oil vapors or the regenerating gas by a compression screw. Such screws, however, are subject tol certain inherent limitations. First, when constructed of abrasion-resistant alloys the cost of such screws is a serious factor in the economics of the process. Secondly, considerable power is required to operate the screw and compress the catalyst, which in turn increases the operating cost of the process. Thirdly, the life of the screw in many instances is relatively short even when constructed of abrasion-resistant a1- loys due to the abrasive characteristics of the catalytic material. Furthermore, in many cases the vcompression of the catalyst adversely affects the activity thereof. For example, it has been found that' the action of Ithe compression screw tends to agglomerate the particles into spheres and pellets having a lower catalyst activity.

One of the primary objects of the' present invention is to provide an improved method of introducing the powdered catalyst into a stream of gases to be reacted which will not be subject to the inherent objections hereinbefore pointed out. Y

A further object of the invention is to provide an improved process of and apparatus for cracking hydrocarbon oils in the .presence of finelydivided catalyst. y

Other specific objects and advantages of the invention will be apparent from lthe detailed description hereinafter in which referencewill be made to the accompanying drawing which is a diagrammatic illustration of an apparatus forming a. par-t of the present invention and capable ure to the fact that the oil vapors must be under a substantial pressure at the time the catalyst is introduced therein. The pressure in the o il .vapors must be, for example, at least suilicient to overcome the frictional resistance of the cracking apparat andthe adjoining fractionating and reilnin equipment to the ilow of the oil vapors 'and It e oil vapor-catalyst mixture therethrough. In commerciall scale cracking equipment of this type, the pressure necessary .to overcome such frictional resistance may be of the order of one atmosphere. Furthermore, in some .cases it is desirable to operate the cracking process under superatmospheric pressure.

It is also desirable in many cases to operate theregeneratlve` equipment under a substantial pressure inprder to reduce the ,size of the equipment'a'nd for other reason's. l

It has been a practice to build up the required of carrying the process into effect. Y

For illustrative purposesthe invention will be described as applied to the catalytic cracking of l hydrocarbon oils, it being understood, as hereinbefore explained, that the invention in its broader phases has amore general application.

Referring to the drawing, the reference character Ill` designatesfa' charge line through which the oil to be cracked is forced by means of pump ,Il into a. heating coil I2 located in furn e-II.

yThe oil, during its course through the heating coil I2, is heated to a temperature suillcient to vaporize at least a substantial portion of the oil. The products from :the heating coil I2 are discharged through transfer line I4 into a separator Il in pressure. on the catalyst to introduce .the same 66 which vapors formed during .the heating thereof separate from unvaporized residue.

The oil employed inthe process may consist of a clean condensate stock, such as a gas oil, or it may comprise a residual stock, such as a topped or reduced crude. In case a clean condensate stock is employed, the separator I5 may be omitted or a by-pass line may be provided around the separator. Unvaporized oil separated in the separator I5 is withdrawn therefrom through line I6. Vapor-s liberated in the separator I5 pass overhead through line Il to an injector I8 having a restricted Venturi nozzle I9. The catalyst is introduced into the injector I8 through a line 20. The' catalyst from line 2U becomes intermixed with the oil vapors in the Venturi nozzle IS of the Y injector I8. The pressure and velocity of the oil vapors introduced into the injector I8 should be suicient to build up a substantial pressure on the resulting mixture of cil vapors and catalyst. The nal pressure imposedpn the oil vapor-catalyst mixture should be at least suicient to overcome the frictio'nal resistance of the cracking equipment and may be higher.

The catalyst introduced into the injector it may be of any suitable character capable of bringing about or accelerating the desired cracking of hydrocarbon oil. Such catalyst may consist, for example, of a naturally active or activated clay or synthetic gels of the same or different chemical composition. The relative amount oi catalyst introduced into the oil vapors may be controlled by regulating a valve in the line 20. The relative amount of catalyst introduced into the oil vapors will depend upon the nature of the feed stock, characteristics of the catalyst, degree of conversion desired, temperature, and other factors. In most cases the concentration of catalyst is relatively high and may range from 0.5 part of catalyst per part of oil toy 10 or more parts of catalyst per part of oil by weight. The oil vapors and catalyst mixture formed in the injector I8 is transferred through line 2| to a reaction chamber 22 in which the oil vapors are retained for a period suicent to obtain the desired degree of cracking. For example, the amount of oil converted into gasoline during passagel through the reaction chamber 22 may range from 20% to 60% ated to condense insufficiently cracked constituor more of the fresh oil. The temperature maintained within the reaction chamber may be, for

example, from '750 to 1000 F'. This temperature' may be maintained by the sensible heat resulting from passing the oil vapors through the preheating coil I2 or the oil vapors irom'separator I5 may be subjected to additional superheating by suitable heating elements (not shown) before being intermixed'with the catalyst. Also a part of theV heat may be supplied by the catalyst introduced into the oil stream.

The time of contact of the oil vapors within the reaction zone may be between 1 and 50 seconds. The velocity of the oil vapors passing through the reaction zone is preferably insufficient to carry the catalyst at substantially the same rate as the oil vapors. As a result, there is a general tendency for the catalyst to settle out of the oil vapors during its passage through the reaction zone. However, the velocity of the oil vapors should be sucient to prevent complete settling of the catalyst. The velocity of the oil vapors may be, for example, between l and 10 feet per second. In such case the density ofthe oil vapor-catalyst mixture within the reactor will be materially higher than the density of the mixture passing into and out -of the reactor. Furthermore, the time of passage of the catalyst through the reaction zone would normally be considerably longer than the 'time required for the passage of the oil vapors through the reaction zone. For example, the resident time ofthe catalyst within the reacents therefrom. The higher boiling 4condensate boiling above the desired motor fuel fraction is withdrawn from the fractionating tower 28 through line 29. Vapors remaining uncondensed during passage through fractionating tower 28 are removed therefrom through line 3i and are passed to a condenser 32 wherein the desired.

motor fuel distillate is condensed. Products from the condenser 32 pass to a receiver 33 wherein liquid separates from uncondensed vapors.

In cases where substantial amounts of steam are employed during the cracking operation, for example, by adding steam to the oil passing through line I4 to separator I5, the water formed by condensation of the steam may be withdrawn from the receiver 33 through line 34 and the liquid distillate may be withdrawn through line 35. Gases separated in receiver 33 are removed therefrom through line 36 and may be rejected from the system or subjected to any 1" urther treatment for the recovery of gasoline constituents therefrom. If desired, a portion of the distillate separated in the receiver 33 may be returned to the top of the fractionating tower as reilux therefor. A kerosene fraction, Diesel oil fraction or heating oil fraction may be segregated in the fractionating tower 28 in a suitable trap-out tray and withdrawn therefrom through line 3l.

Returning to the reaction chamber 22, it is sometimes desirable to recirculate a portion of the catalyst removed from the reaction chamber back to the inlet thereof. In other cases it may be desirable to recirculate all of the catalyst for a definite period of time. In such cases a part or all of the products removed from the reaction chamber 22 may be passed through line 38 to a suitable separator, such as a cyclone separator 39, for segregation of the lcracked products from the catalyst mixture. The crackedproducts in the cyclone 39 are transferred through line 4I and line 21 to the fractionating tower 28 for fractionation as just described. The` catalyst separated in the cyclone 39 vdischarges into the conduit or pipe 2l) from which it is passed into the injector I8 for recycling to the cracking chamber.

For simplicity a single cyclone separator has been shown for separation of the catalyst from the oil vapors. However, it may be desirable to provide-a plurality of such cyclones arranged in a series or to provide other suitable separating device in lieu of or addition to the cyclone separators. v l

As previously mentioned, a part of the catalyst may -be continuously recycled to the reaction chamber through lcyclone separator 39 and pipe 20 while the remainder is regenerated, or all of the catalyst may be recycled for a limited period, after which all of the catalyst will be passed to a regenerating circuit now to be described.

Referring again to the cyclone separator 25,

catalyst separated therein discharges through f aseos nnoot u into which an inert stripping gas is discharged through line 41 at a pressure and velocity suiiicient to develop additional pressure on the outgoing mixture of gas and catalyst. The-- inert gas employed as a stripping and carrier medium for the catalyst may consist of steam,

carbon dioxide, spent combustion gases, nitrol gen, or the like. Such gas may be introduced into the system through .1ine48 and transferred to the injector 48 through lines 41.

The mixture of stripping gas and catalyst formed in the injector 48 is transferred through line 48 to a further cyclone separator 49 or other equivalent device for the separation of the catalyst from the stripping gas. This stripping gas separated in the separator 49 may contain small amounts of residual hydrocarbon vapors remaining on the catalyst after separation from the cracked vapors in the cyclone 28. In view of this, the stripped gas containing the hydrocarbon vapors may be passed throughlines l and 52 to line 21 wherein stripping gasisintermixed Y with the cracked products. If desired, a part or all of the stripping gas may be rejected from 5 the system through line 88 and, if desired, passedl to other apparatus for the recovery of oil therefrom. Y

In some cases it is preferable to recycle catalyst -to the reaction zone after it has been subjected to a stripping gas such as steam. To this end a. line 89 leading from line 48 toline 8| is provided whereby the suspension of catalyst and stripping gas can be passed through lines-,189,v 8l

iocity of the regenerating gas passing .through the regenerating Yzone, the length of time the catalyst is subjected to, regeneration may be controlled over` an extended range.

The suspension oi regenerated gas and catalyst after passing through regenerator 12 is withdrawn through line 18 and may be passed through line 14 to a separator 15 adapted to separate the powdered regenerated catalyst from the regenerating gas. The regenerating gil Seprated in the separator 18 is removed therefrom through line 18 and may be rejected from the system or it may be passed to suitable heat exchangers for the recovery of energy therefrom. .The regenerated catalyst separated in the separator 18 is transferred through pipe 11. to .an injector 18 A having a restricted throat 18 into which is in- Y.iectcd a streamsoinertstrixping and conveying gas introduced through line 8l.l Th'e' amount additional pressure on the resulting mixture. The suspension of stripping 4gas and catalyst formed in the injector 18 is transferred through line 8|, which in turn merges with line 88 leading to the separator 89. 'Ihe regenerated cata'- jflyst is separated from the stripping or carrier gas in the separator 88 andthe regenerated cata-v steam or other inert gas from line 48 may be introduced into the injector 58 through line 51 to effect additional stripping action on the catalyst. 111e resulting mixture of stripping gas and cata` lyst pases through line 88 into a further cyclone separator 58 wherein the stripped catalyst separatesfrom the stripping sas. -Thestrippins gas is withsrswnrmm the separator se through une v :igeaigmaybe'rejectedfromthbsystemthrough catalyst separatedinthecycbne sepsratordisehargesthroughline intoaninviector 81 having a restricted throat. into which anoxidizinggagsuchasnirorairdilntedwith other inert gases, is introduced through liney 88.-' I l'ie amount and velocity 'of air introduced into theiniector81iss|rmcienttobaildupadditionai pressureonthecatalyst-airmixture sothat at thisstagethepresureisatleastmcient'to overeomethetriciionalresistanceoitheregeneratingsystelntotheilow,otthecatalystgasmix tureandmaybesumclentlyhightocarryoutth'e regenerativetreatlnent under-substantial saperlyst is discharged through line.20'int0 the inlector I8 where it remixes with fresh oil vapors.

In carrying out a -process of this sort wherein catalyst is transferred continuously from a reaction zone to a regeneration zone and from the regeneration lzone to the reaction zone,V it is generally necessary to keep the reactants separated from the regeneration medium. In the present example wherein hydrocarbons are the reactants l and air is the regeneration medium, segregation I is imperative. When the system.- is in normal operation, the level of catalyst in pipes 28, 42, 84, '8 8 and 11 leading to the injectors I8,` 48, 88. 81 and 18, respectively, will maintain the desired iseal between the cracking and regenerating sections o! the equipment. Furthermore, theuse positive seals may be provided. Por example.

sucheealsmaybemechanicaidevicesresponsive to abnormal conditions or a'eoiid mass ofpdeaerated catalyst may be interposed between the two parts of themxipment. In the present proceas,theuseofmechanicalmovingpartsisavoided by employingA a h'ead of'catalyst powder' asthe Itwillbeobservedthatthepresentproceea avoids the use of large storage l'mppers, intermediatelockhoppemand convesingsystemsand conduitsinwhichcatalystistransferredindeme' phase. muy, the'amount ot catalyst preeentinthesystemwhichisnotactmllyin useintlmreactioncycleormdergoingrege'nen tionisreducedtoaminimum.

catalyst mlrbebrpassedtbemmlicnofregenerated separator 39. yIn such case the regeneration gases y are withdrawn from thev separatori-39 through lines 4l and 82, and the separated catalyst is returned tothe reaction zone by way of line and injector i8. `Where a portion of the catalyst is recirculated directly through lines 23 and 38, the regeneration gases should be separated from the catalyst in separator l5 and the catalyst should be transferred to separator '3g by means of an inert gas injected through line Bil in order to avoid mixing of hydrocarbon vapors andregeneration gas in separator 3S. On the other hand, a part of the twine-stripped catalyst from stripping conduit 53 may be returned to the cracking zone by passing it in suspension through lines 99, 8l, cyclone separator i9 and line 2i).

In some cases it is also desirable to recirculate a portion of the catalyst removed from theregenerator back into the regenerator rather than passing it to the cracking zone. When 'operating in this manner, a portion of the stream of regenerating gas vand catalyst withdrawn from the regenerator 'l2 through line 'i3 may be passed through line 8i to separator 59 from which the catalyst is returned to the regenerator through line 66, injectorl Bl, and line lli.

While the drawing shows two separate stripping steps for separating hydrocarbon oil vapors between the cracking and regenerating systems, it will be understood that only one step may be employed and in some cases the stripping step may be completely eliminated. In the latter case, the air or other oxidizing gas from line 3 may be passed through lines 85'and l? to the injector :i3 and the resulting suspension of air and catalyst may be passed from injector d3 through lines 86 and 87 to the regenerator l2.

In cases where one stripping stagel is employed, *he air or other oxidizing gas for regeneration may be passed from line 6a through lines E8 and 5l to injector 55 and the resulting suspension passed through lines 8l and 85 to the regenerating chamber l2. In either or the above cases the injector 6l may be used solely for recirculating catalyst to the regenerator '32. In such case the catalyst recirculated to the regenerator may be subjected to a cooling operation to control the temperature therein.' n

The temperature of the regenerator should be regulated to avoid permanently impairing the activity of the catalyst. yIn most cases it isdesirable tomaintain the temperature below about 12007 F. l

Fresh catalyst may be introduced 'at lany de-` eupior that sir-ed .point inthe system to mak lost inoperating Ythe process.

lThe present invention thus provides a contin-v uous` process for carrying out reactions in the presence of nely-divided solid andan apparatus therefor which isV substantially free v of4 moving parts'.` yTlie'invention also provides'a process for increasing the pressureon powder byttransierring it from a zone'of lower pressure to a `vzone of.'v higher-pressurebymeans of injectorsfra'ther thanf by compression screws or other mechanical devices.v Furthermora'it provides a. process for the continuous circulation of a', powdered material through a plurality of zones' containing vapors Vwhich are incompatible withone another.

Having described the preferred embodiment of the-invention, it will be understood'that it embraces such other variations and modications as come within the spirit and scope thereof.

What is desired to be protected by Letters Patent is:

1.'In the catalytic conversion of hydrocarbon oils, wherein nnely-divided 4catalyst isr injected into a stream of oil` vapors to be converted, the resulting mixture passed through a conversion zone, the catalyst thereafter separated from the conversion products, the catalyst so separated treated with an inert gas toremove volatile hydrocarbons retained thereon following the separation Vthe improvementin the ,method of removing said volatile constituents which comprises passing a stream of inert gas through a restricted throat under a substantial pressure and at a vveiobity suflicient to develop a low pressure area adjacent the entrancer of said throat, introducing separated catalyst into said low pressure area to thereby subject said catalyst to low presl sure treatment and to injectj'said catalyst into the stream of inert stripping gas passing through said throat and thereafter separating the stripped catalystfrom said inert gas.

2.-*1n the catalytic' conversion of hydrocarbon oils wherein nely-divided catalyst is injected into a stream of oil vapors,v to 'be' converted, the resulting mixture passed through a conversion zone, the conversion catalyst thereafter separated from' the conversion products, the conversion catalyst so separated treated with an inert gas to remove volatile hydrocarbons retained thereon following said separation;l the improvement in the method of removing volatile constituents retained on said catalyst which comprises passing a stream of inert stripping gas through a restricted throat under a substantial pressure and at a velocity suflicient4 to develop a low pressure area adjacent the entrance to said throat, introducing the separated catalyst into said low pressure area tothereby subject said catalyst to'low pressure treatment and to inject said catalyst into the stream ofJ inert stripping gasythereafter separating the catalyst'vfrom saidv inertigas, passing a second stream of stripping gas through a second i restricted throat under a pressure substantially -named throat, introducing catalyst separated from said strippinggas intovsaidllastmamed low pressure area to again subjectsaid kvcatalyst to` low pressure treatment and to injectsaidcatalyst intoa'l second streaml ofstrippinggas and there..

i afterseparating the stripped catalyst from said second stream of stripping gas. y

., JO Cl MUnDaY. 

